I swapped out the optical drive in my laptop in lieu of a second internal drive, with this fantastic kit by MCE. I've taken apart my laptop four or five times now, but these step-by-step guides by iFixit are a great resource.

I divided my 500GB drive into two partitions. The first is a 60GB partition dedicated to Time Machine to act as my system backup. The second partition is a 440 GB storage disk, where I can store my media and larger files.

Okay, so I didn't really upgrade all that much, but it's a laptop.

I still like this old machine, for a variety of reasons (although those reasons will soon diminish once the Thunderbolt hardware starts to hit the shelves). The primary perk of my 15" Non-Unibody Macbook Pro is the extremely useful ExpressCard slot on the side. With it, I can add two eSata ports, or connect SxS cards directly into my laptop, both of which are very useful for on-set data management.